Electrical switching between exciton dissociation to exciton funneling in MoSe<sub>2</sub>/WS<sub>2</sub> heterostructure.

Meng, Yuze; Wang, Tianmeng; Jin, Chenhao; Li, Zhipeng; Miao, Shengnan; Lian, Zhen; Taniguchi, Takashi; Watanabe, Kenji et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

The heterostructure of monolayer transition metal dichalcogenides (TMDCs) provides a unique platform to manipulate exciton dynamics. The ultrafast carrier transfer across the van der Waals interface of the TMDC hetero-bilayer can efficiently separate electrons and holes in the intralayer excitons with a type II alignment, but it will funnel excitons into one layer with a type I alignment. In this work, we demonstrate the reversible switch from exciton dissociation to exciton funneling in a MoSe<sub>2</sub>/WS<sub>2</sub> heterostructure, which manifests itself as the photoluminescence (PL) quenching to PL enhancement transition. This transition was realized through effectively controlling the quantum capacitance of both MoSe<sub>2</sub> and WS<sub>2</sub> layers with gating. PL excitation spectroscopy study unveils that PL enhancement arises from the blockage of the optically excited electron transfer from MoSe<sub>2</sub> to WS<sub>2</sub>. Our work demonstrates electrical control of photoexcited carrier transfer across the van der Waals interface, the understanding of which promises applications in quantum optoelectronics.